Hanging wall, footwall, slip vector, net slip, rake কী?

Let a fault be locally a plane that is not vertical. The hanging wall is the block above it, the footwall the block below it. Let $A$ be a point of the footwall and $A'$ the point of the hanging wall that was in contact with it before the movement. The slip vector $\overrightarrow{AA'}$ is the displacement of the hanging wall relative to the footwall; its length is the net slip. The rake $r$ (also called the pitch) of the slip vector is the angle, measured in the plane of the fault, from the strike direction given by the right-hand rule to the slip vector, positive when the slip vector points up the plane and negative when it points down it: $-180{}^{\circ} < r \le 180{}^{\circ}$. This is the seismologists’ convention, used again for earthquakes in Chapter 18; many field geologists record instead an angle between 0 and $180{}^{\circ}$, measured clockwise from the strike seen from above, and add the sense of movement in words.